translated from Spanish: Chilean scientists study REM sleep disorder as a backdrop of Parkinson’s disease

speed of eye movements on a normal night’s sleep. REM sleep takes up 25% of the total night rest hours in a human being, and is repeated, every ninety minutes, in blocks of 20 or 25 minutes, up to five times in this period. While sleeping, people go from a restful, restful, second sleep state marked by great mental activity. 
“It is during REM sleep that in the minds of sleeping people we experience the most intense and implausible stories, full of emotions and colors, that, we usually remember fleetingly and vaguely when we wake up. and we call dreams,” explains Adrián Ocampo, associate professor at the Institute of Biomedical Sciences (ICBM) at the University of Chile.
The intense dream activity of REM sleep – running, flying, fighting, kicking a ball, for example – does not become a motor action because the brain causes paralysis of the limbs, which disappears upon awakening. This physiological paralysis we experience every night – transient and irreversible – is produced by a small nucleus of the brain, and avoids behaviorally manifesting what we dream. Once the REM is finished, the lock disappears; whether the individual wakes up or returns to sleep.
“Very rarely, a small lesion can occur that affects the nuclei that generate sleep paralysis. That’s when dream activity can be freed from paralysis and people act sleep, causing significant sleep injuries. It is what is called REM Behavioral Sleep Disorder (REM),” says the academic of the U Faculty of Medicine. From Chile.
Diagnosis of this condition is made by a test called video-polysomnography, in which the patient is recorded throughout the night, documenting their behavior and biological signals of the brain and muscles.
A more effective diagnosis
The REM phase is the fifth stage of sleep, characterized by accelerated eye movement and part ly part approximately one and a half hours after the start of rest. In this cycle, blood pressure and heart rhythm accelerate, blood pressure increases and it is impossible to control the body’s temperature. Brain activity can be even higher than when we’re awake.
The injury that characterizes REM disorder – first described 30 years ago in cats and mice – presages the development of Parkinson’s disease in a decade, as yet without a cure. Dr. Ocampo points out that the relationship between the two diseases, according to scientific evidence accumulated since the 1990s, is that the progression of neuronal damage caused by the REM over 40 years would lead to ten or fifteen years in the Párkinson.
“Neurodegenerative diseases (including Parkinson’s disease) cause a gradual destruction of neurons in the brain. In the early stages of Parkinson’s disease, injuries can eliminate the mechanism that causes REM sleep paralysis by causing REM Sleep Behavioral Disorder. These patients, and especially the cohabitants, report that from some time and already entered adulthood, subjects act the dream during the nights. This is a very striking condition and not to be confused with sleepwalking that is typical of childhood or adolescence,” explains the Chilean scientist.
Parkinson’s disease can affect 1% of adults over age 60. Diagnosis is made when typical disorders known as parkinsonism (stiff limbs, tremor, slow movement) develop); However, long before the onset of these signs (at least ten or fifteen years), patients show signs that may alert about the occurrence of the disease. 
Linking is that neuronal damage from The Párkinson, as well as other synucleinopathies, can affect sleep paralysis circuits early. “Injuries to Parkinson’s disease are affecting progressively. There is evidence that they first affect peripheral nerves and then advance toward the spinal cord and brainstem. More late they affect the nigra subtancia responsible for the phenomena of parkinsonism. The time it takes between affecting the nucleus of REM sleep paralysis and nigra substance is about ten years,” the ICBM academic complements.
A precision model
The ICBM Sleep and Chronobiology Laboratory team has developed, in the context of a doctoral thesis, a method of analysis that seeks to more accurately detect REM sleep disorder and, therefore, anticipate in a decade the damage of conditions Neurodegenerative. CTE is usually detected in a visual examination in which the doctor observes the patient’s sleep activity, but if the patient did not have obvious behavioral manifestations, the diagnosis becomes unlikely. 
In this way, the purpose of the project is to obtain a highly sensitive and specific system in the signal of the muscles registered in clinical polysomnography, details the scientist of the Faculty of Medicine of the University of Chile.
“Research of motor events today is fundamentally visual image and muscle logging. When there is a disorder fully developed the image of the moving person is eloquent enough to contribute to the diagnosis, the problem is that they are the least. Most cases only manifest minimal changes in muscle tone, and not violent behaviors, which are occasional. Agreeing that the person acts the dream at the time of registration is a lottery.”
To address this gap, studies led by Dr. Ocampo, in collaboration with academics from the University of Innsbruck in Austria, aim to look at aspects of muscle registration (electromyogram), which are not easily discernible even in the eye of the Expert. This new analysis can establish what type of activity is observed during the study.
Dr. Ocampo details that patients with the disorder develop a very characteristic pattern that allows them to be discriminated against from normal patients by quantitative, unbiased analysis and based on the properties of the muscle signal. “Our method allows for high reliability to establish that a patient exhibits abnormal activity, and that it could correspond to REM sleep behavioral disorder.”
The academic warns that one of the problems of current methods in the investigation of sleep disorders is the high cost in hours of evaluation involving polysomnographic analysis, a true “bottle neck”. “We are working on a simple and robust method based on the properties of the muscle signal, which is very reliable and can be employed as a support to the clinical neurophysiologist specialist. One projection of epidemiological relevance is that our method can be easily implemented in a telemedicine environment,” he says.
Ten years before the Párkinson
The link between TCR and neurodegenerative diseases (in addition to Parkinson’s also relates to multisystem dystrophy and Lewi body dementia) in the context of population aging, make this sleep condition increasingly taking on epidemiological value. Among these pathologies, The Párkinson has the greatest impact: it is the second leading cause of neurodegeneration dementia in humans.
REM behavioral sleep disorder disease tended to be confused until the 1990s with sleepwalking, but then, in the 1990s, it was established that its appearance in people over 40 marked the onset of progressive neuronal damage related to neurodegenerative pathologies. The academic of the Faculty of Medicine of the University of Chile stated that it is not a cause or trigger of subsequent neurodegenerative pathologies, but an early evidence of the alteration of proteins linked to the death of neural tissue.
“It is not yet known how to stop this process, but by studying sleep, we can determine well in advance the risk of the onset of these diseases,” says the Chilean scientist. 
In Chile, there are no figures regarding the prevalence of REM sleep disorder. The national health survey includes some general questions about sleep, but not specific questions about sleep. Dr. Ocampo concludes that a major faction of older adults developing neurodegeneration could anticipate their condition with a timely investigation of REM sleep behavioral disorder. Because The Párkinson is still a disease without a cure, such information could be useful in terms of recommendations for better management of risky behaviors. 
“The challenge is to find biomarkers that anticipate Parkinson’s, to project risks of future disease and eventually through new therapeutic strategies patients can improve their prognosis. But this challenge is still a world of questions for science,” says ICBM’s associate professor.

Original source in Spanish